Separation of lithium from lithium bearing micas and amblygonite



ite

This invention concerns the separation and recovery of lithium valuesfrom lithium-bearing micas, such as lepidolite, and from amblygonite.More specifically, it concerns a process in which a lithium-bearing micaor amblygonite is subjected to high temperature attack with a stream ofsulfur trioxide for a relatively short time and to the subsequentaqueous extraction of enriched lithium values from such treatedlithium-bearing ore. This application is a continuation-in-part ofapplication Serial No. 575,972 filed April 4, 1956, now abondoned.

Until the present time, lithium values have been separated and recoveredfrom lithium-bearing ores by prolonged fusion processes and completedissolution of the ore. Thus, tedious, time-consuming reactions andseparation processes had to be resorted to in the past in order torecover a purified lithium salt. See, for example, Schieffelin,Manufacture of Lithium from Lepidolite, J]. Soc. Chem. Ind. 27: 549-550(1908), and Weidrnann U.S. 'Patent No. 1,544,114, patented June 30,1925. Furthermore, the ores first had to be finely ground before beingprocessed according to the prior art.

It has now been discovered, in accordance with this invention, that alithium-bearing mica or amblygonite in coarsely particulate orsub-divided form can be reacted at an elevated temperature ranging fromabout 600 to about 900 C. with a stream of S0 for a relatively shorttime so as to render lithium values water-soluble without at the sametime dissolving the ore matrix. Aluminum andv iron values are notattacked thereby, rendering subsequentseparation and recovery of lithiummuch less diificult and considerably more satisfactory with respect tohigh purity and high recovery of lithium salt. The lithium values, assulfate concentrate, are thereafter dissolved out in water and can berecovered in a highly purified form, such as lithium chloride, bytitrating the aqueous concentrate with the requisite amount of aqueousbarium chloride to precipitate the sulfate, filtering the chloridesolution, evaporating water from the filtrate, and extracting thelithium chloride therefrom with n-amyl alcohol and evaporating thealcohol.

The amount of S0 used must be sufficient to react 'with the boundlithium, but otherwise is not critical, since unreacted S0 can berecovered for re-use. The 80,;

'can be formed catalytically in known manner, during or immediatelybefore itsreaction with the lithium-bearing mica or amblygonite from amixture of S0 and 0 advantageously by passing a mixture of S0 and 0 overa conventional'platintnn-on-silica gel catalyst or equivalent at 450 C.or above in the usual way. Also, While oxygen will react with S0 in thepresence of iron impurity present in lepidolite and amblygonite atreaction temperatures of 600 to 900 C. to form S0 S0 and air will notreact appreciably under similar conditions to form S0 even when excessair over theory is present.

The temperature of reaction ranges from about 600 to 900 C. Below 600C., dissolution of the ore takes place and iron and aluminum, inparticular, are attacked and rendered water-soluble. Above 600 and up to900 0, however, the ore matrix is not attacked and the iron and aluminumvalues are not rendered soluble.

The reaction time varies with the batch size and temperature used.Generally one to two hours is sufiicient within the temperature range of600 to 900 C. In any i event, a test run sufiices to indicate a timesufficient to solubilize the lithium content.

The process of this invention is operable with lithiumbearing micas andamblygonite'only. Spodumene, for example, is not operable in thisprocess, even with prior preheating at 1100 C. to transform it tobeta-spodumene. When it is attempted to react spodumene orbeta-spodumene with S0 at 600 C. to 900 C., only a negligible amount oflithium is thereby rendered soluble.

The following examples represent specific embodiments of this invention.Parts and percentages therein are by weight. In each example, a quartzreactor provided with a condenser followed by a filter to removeentrained mist was charged with coarse particles of lithium-bearing micaor amblygonite, inch being the largest dimension. Each charge wastreated at about 600 to 900 C. with a stream of S0 carried by He, or amixture of S0 and 0 forming S0 under conditions of reaction, or with astream of per se, the S0 being in excess of that required. to transformthe lithium values to Li SO Any gas which is inert under conditions ofreaction, such as helium, neon, argon, nitrogen, etc., can be used as anS0 carrier. The so-treated charge was transferred to a Soxhlet thimbleand leached in water. The aqueous solution so obtained was evaporated toobtain the weight of the salt, and dried at C. Anhydrous lithiumchloride was obtained by (l) titrating the salt solution with therequisite quantity of aqueous barium chloride solution to precipitatethe sulfate; (2) filtering the resulting chloride solution; (3)evaporating the water from the filtrate so-obtained; (4) extracting thelithium chloride from the resulting residue with n-amyl alcohol; (5)evaporating the alcohol, from the solution, so obtained, as by blowing agentle stream of dry nitrogen into the alcoholic lithium chloridesolution.

EXAMPLE 1 Time Charge Operation Temp., C.

0 550 Started passing He through 18 g. liquid S03 at rate of mL/min.

55mins 890 Heat off; S03 off (15 g. SO;

vaporized).

2 hrs. 5 mins Weight of lepidolite charge: 14.9493 g.

Weight gain of SO -treated charge=1.5775 g.

Weight of condensate from reactor efiiuent=0.2540 g. Weight of dried, HO-leached residue=13.0444 g. Weight of extracted salts (Li SO -H O,KLiSO etc.)=3.4638 g.

Lithium balance:

Li O content of initial charge=0.623 g.=4.l7 wt.

percent Li 0 content of dried, H O-leached solid residue=0.070 g.=0.54wt. percent Percent Li removal=88.8%

Weight of lepidolite charge-=8.6139 g. Weight gain of SO -treatedcharge=1.2993 g. Weight of condensate=1.0l96 g.

3 Weight of dried, H O-leached residue=7.8970 g. Weight of extractedsalts (Li SO -H O, KLiSO etc)= EXAMPLE 3 Time Temp., C. Operation 500Started SO: flow at rate of 0.41 gJmin.

35 min 900 Started 02 flow at rate of 137 ml./min. S03 formed in situ.

2 hrs. mms 860 Hiating current 011, S02 off,

Weight of amblygonite=l8.1887 g.

Weight gain of SO -treated charge=2.1763 g. Weight of dried, H O-Ieachedresidue=15.9296 g. Weight of extracted salts=5.1189 g.

Among the advantages of the process of this invention over the prior artare 1) the lithium-containing mica or amblygonite need not be finelyground before reaction with S0 (2) the ore matrix is not attacked anddissolved, thus it is much less difiicult to separate lithium fromassociated impurities; (3) the reaction is not time consuming; (4)aluminum and iron are not dissolved, therefore less reagent S0 isneeded; (5) unreacted S0 is readily recirculated.

EXAMPLE 5 Crushed lepidolite containing quartz was heated at 600 C. forone hour in a quartz reactor while exposed to a stream of a mixture ofS0 and air (nun 1) and at 300 C. for one hour in the presence of amixture of S0 and air (run 2). In contrast thereto, runs 3 and 4utilized 80;; at 600 C. and at 630 C., each for one hour, the 80;,having :been prepared catalytically by passing a mixture of S0 and 0over a conventional platinum-on-silica-gel catalyst at 450 C. The amountof S0 oxidized to S0 was equivalent to the S0 present in the mixtures ofruns 1 and 2. The sulfated lithium values were extracted with water andrecovered. In runs 1 and 2, more than sufiicient air was present tooxidize the S0 to S0 if a catalytic reaction were used. Runs 1 and 2concern experiments outside the scope of the invention and are includedfor purposes of comparison.

'Results are summarized in the following table.

Table Run 3 S 03 (from Run 1 (Blank) Run 2 (Blank) S02 70 ml./ Run 4 S03(from S0: 70 ml./ S02 70 ml./ min. and Oz S02 70 ml./ min. air 180 min.air 180 90 ml./min. min. and 01 mlJmin. 600 m1./rnin 800 catalyzed at 90mLImin.) C. for 1 hr. 0. for 1 hr. 450 0.) 600 630 C. for 1hr.

C. for 1 hr.

Wt. lepidolite cum quartz, grams-.- 19. 5607 14. 7432 14. 7545 16. 7847Wt. gain, grams 0. 7497 0.0235 4. 8758 5. 5076 Wt. dried Water-leachedcharge,

grams 18. 7841 14. 0790 12. 2704 13. 9063 Wt. extracted salts, grams 1.3955 0. 0560 8. 9175 10. 4847 Lithium Balance:

LirO content of lepidolite charge wt. percent 3.01 3. 01 3. 01 3. 01 Wt.Lind) in charge, grams o. 595 0. 44s 0. 449 0. 510 Wt. LirO inextracted'salts 0. 043 0.006 0. 232 0.273 Percent L120 removal (based onextracted salts) 2 1. 3 52. 2 53. 8

Lithium balance:

Li O content of charge=2.057 g. Li O=11.3 percent Li O content of dried,water-leached residue=0.669

g.=4.2 percent Percent Li remova1=67.5 percent EXAMPLE 4 Time Temp., O.Operation 0 600 Started S02 flow at rate or 0.25 gJmin. Started or flowat rate of 95' m1./min. 25 0., 1 atm. SO; formed in situ.

1% hrs 910 2 hrs 890 Heating current oft, Son 011,

N 2 on.

Weight of lepidolite cum quartz=16.0395 g.

Weight gain of SO -treated charge=1.6060 g.

Weight of dried, H O-leached residue=13'.3941 g. Weight of extractedsalt dried at 150 C.=4.0293 g.

Lithium balance:

L120 content of lepidolite cum quartz=0.5518=3.44

wt. percent Li O content of dried, H O-Ieached residue= 0.0575==0.43 wt.percent Percent Li removal=89.5%.-

References Cited in the file of this patent UNITED STATES PATENTS876,851 Wadman Jan. 14, 1908 1,402,831 Brown Jan. 10, 1922 1,710,556Grisewald Apr. 23, 1929 1,742,191 Arnold Jan. 7, 1930 2,016,222 BassettOct. 1, 1935 2,516,109 Ellestad July. 25, 1950 OTHER REFERENCES Welch:Scientific Journal of Royal College of Science, vol. 14, pages 12-18,Royal College of Science, London, 1944.

1. A METHOD OF SEPARATING LITHIUM VALUES FROM A LITHIUM ORE OF THE GROUPOF LITHIUM-BEARING MICAS AND AMBLYGONITE WHICH COMPRISES SUBJECTING SAIDLITHIUMBEARING ORE TO THE ACTION OF SULFUR TRIOXIDE AT A TEMPERATUREBETWEEN 600* AND 900*C., IN AMOUNT AND FOR A TIME SUFFICIENT TOTRANSFORM LITHIUM VALUES TO LITHIUM SULFATE AND RECOVERING ENRICHEDLITHIUM VALUES THEREFROM.